Introduction to Modified Gravity: From the Cosmic Speedup Problem to Quantum Gravity Phenomenology

Olmo, Gonzalo J.

doi:10.48550/arxiv.1112.2223

Cited by 5 publications

(5 citation statements)

References 9 publications

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“…A wide variety of modifications to GR can be characterized by higher-order curvature terms in the action. This alternative theories have been studied since the middle of the last century, with the aim of solving some of the theoretical problems listed above, and more recently for giving an explanation to the dark phenomena as well, without a clear success in their resolution (see [23][24][25][26][27][28] and references within). From a physical perspective, higher-order curvature terms are well motivated for several reasons.…”

Section: Introductionmentioning

confidence: 99%

Effective interactions in Ricci-Based Gravity below the non-metricity scale

Delhom¹,

Miralles²,

Peñuelas³

2020

Eur. Phys. J. C

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We show how minimally-coupled matter fields of arbitrary spin, when coupled to Ricci-Based Gravity theories, develop non-trivial effective interactions that can be treated perturbatively only below a characteristic high-energy scale ΛQ. Our results generalize to arbitrary matter fields those recently obtained for spin 1/2 fields in [1]. We then use this interactions to set bounds on the high-energy scale ΛQ that controls departures of Ricci-Based Gravity theories from General Relativity. Particularly, for Eddington-inspired Born-Infeld gravity we obtain the strong bound |κ| < 10 −26 m 5 kg −1 s −2 . PACS numbers: arXiv:1907.05615v1 [hep-th] 12 Jul 2019 3 With the well known exception of Lovelock theories [65]. 4 Known as Einstein-Cartan-Sciamma-Kibble or ECKS theory. 5 If one considers coupling spinors to GR this is not strictly true, since there arise torsion corrections sourced by spin-density. 6 In fact, the class of RBG theories, which contains f (R) theories, can be defined as the most general class of theories with projective symmetry and whose Lagrangian is given by an analytic scalar function of the metric and the Ricci tensor.

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Section: Introductionmentioning

confidence: 99%

Effective interactions in Ricci-Based Gravity below the non-metricity scale

Delhom¹,

Miralles²,

Peñuelas³

2020

Eur. Phys. J. C

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“…It is inferred that by making use of the modified scalar functions, the evolutionary behavior of realistic astrophysical objects can be discussed. Olmo [5] over-viewed the Newtonian framework and devoted their attention towards Nordström's scalar theory and its impact on Einstein's GR. They also presented the cosmic speed-up issue and inferred that several quantum gravity issues can be well addressed by the Palatini f (R) gravity and f (R, Q) theories [6].…”

Section: Introductionmentioning

confidence: 99%

Role of Structure Scalars on the evolution of Compact Objects in Palatini $f(R)$ Gravity

Bhatti,

Yousaf,

Tariq

2021

Preprint

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The utmost concern of this article is the construction of modified scalar functions (structure scalars) by taking Palatini f (R) gravitational theory into account. At first, a general formalism is established in which we assess gravitational stellar equations by putting into use the Palatini's technique. Later, from the perspective of tilted observer, we Lorentz boosted the components of energy-momentum tensor using relative velocity ω. To examine the physical as well as mathematical aspects of the fluid source, we carry out a detailed analysis of kinematical variables by evaluating shear tensor and scalar, four-acceleration and expansion scalar. For the fluid content inside our spherical star, we inferred the mass function (geometric mass) and the active gravitational mass. Raychaudhuri equation, Bianchi identities in addition to few other equations are worked out to discern the structure formation and analyze the object's evolutionary stages. The Riemann tensor is then broken up orthogonally to set up few scalar functions connected with fundamental physical characteristics of the fluid source like energy density, effects of tidal forces and anisotropic stresses etc.

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“…As a consequence of the difficulties of solving these questions, alternative theories of GR have been developed. For a review see [2][3][4]. Here the f (R) gravity theory is considered.…”

Section: Introductionmentioning

confidence: 99%

$f(R)$ gravity and Tsallis holographic dark energy

Ens,

Santos

2020

Preprint

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Introduction to Modified Gravity: From the Cosmic Speedup Problem to Quantum Gravity Phenomenology

Abstract: Chapter written for the book "Aspects of Today's Cosmology", Edited by: Antonio Alfonso-Faus, InTech Publishing, Rijeka, Croatia, (2011), ISBN 978-953-307-626-3. The properly formatted version (26 pages) can be freely downloaded from the publisher's website.

Cited by 5 publications

References 9 publications

Effective interactions in Ricci-Based Gravity below the non-metricity scale

Effective interactions in Ricci-Based Gravity below the non-metricity scale

Role of Structure Scalars on the evolution of Compact Objects in Palatini $f(R)$ Gravity

$f(R)$ gravity and Tsallis holographic dark energy

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